Battmer Rolf, Pesch Joerg, Stöver Timo, Lesinski-Schiedat Anke, Lenarz Minoo, Lenarz Thomas
Department of Otolaryngology, Medizinische Hochschule, Germany.
Otol Neurotol. 2006 Oct;27(7):918-22. doi: 10.1097/01.mao.0000235374.85739.c6.
Perimodiolar intracochlear electrodes with contacts facing towards the modiolus have limited current flow towards the outer wall of the cochlea and therefore, may reduce the occurrence of facial nerve stimulation (FN) in cochlear implant subjects.
Facial nerve stimulation is a well-known complication in cochlear implant treatment especially in the group of subjects with otosclerosis. The possible explanation of this side effect is a change of the electrical properties of the otosclerotic bone leading to leakage current and resulting in facial nerve stimulation.
Four CI subjects who had been implanted with a Nucleus Mini22 device with a Nucleus Straight electrode between 9 to 12 years ago suffered from severe FN stimulation. Electrode contacts had to be switched off so that they could only use 4, 11, 13, and 15 electrodes of their usual set of 22. The switch off resulted in deteriorating speech understanding over time. Therefore, all subjects were reimplanted with a Nucleus 24R device with a Contour electrode. Preoperatively, the threshold of FN stimulation was obtained on all electrodes subjectively. Intraoperatively, FN stimulation thresholds were measured objectively with both, the old and the new device and were compared. NRT and SRT thresholds were also obtained with the reimplanted device to assure effective electrical stimulation of the auditory nerve.
In all four cases the postoperative fitting demonstrated no FN stimulation on all electrodes up to maximum comfortable level. The insertion of the Contour electrode array was complete in three cases, in one case the array could only be inserted partially similarly to the situation before the reimplantation. Speech perception tests showed a significant improvement in all subjects with the new device.
Electrodes with modiolar facing contacts and perimodiolar position like the Nucleus Contour electrode reduce the possibility of facial nerve stimulation significantly due to more focused electrical stimulation.
电极触点朝向蜗轴的耳蜗内周缘电极向耳蜗外壁的电流传输受限，因此，可减少人工耳蜗植入者面神经刺激（FN）的发生。
面神经刺激是人工耳蜗治疗中一种众所周知的并发症，尤其是在耳硬化症患者群体中。这种副作用的可能解释是耳硬化骨的电学特性发生改变，导致漏电流，进而引起面神经刺激。
4名在9至12年前植入了带有Nucleus Straight电极的Nucleus Mini22装置的人工耳蜗植入者遭受了严重的FN刺激。电极触点不得不关闭，以至于他们只能使用其通常的22个电极中的4个、11个、13个和15个电极。随着时间的推移，关闭电极触点导致言语理解能力下降。因此，所有受试者均再次植入了带有Contour电极的Nucleus 24R装置。术前，主观获取所有电极上的FN刺激阈值。术中，使用新旧两种装置客观测量FN刺激阈值并进行比较。还使用再次植入的装置获取NRT和SRT阈值，以确保对听神经进行有效的电刺激。
在所有4例病例中，术后调试显示在所有电极上直至最大舒适水平均未出现FN刺激。3例病例中Contour电极阵列插入完整，1例病例中阵列只能部分插入，与再次植入前的情况类似。言语感知测试显示，所有受试者使用新装置后均有显著改善。
与Nucleus Contour电极一样，电极触点朝向蜗轴且位于耳蜗内周缘位置的电极，由于电刺激更集中，可显著降低面神经刺激的可能性。
